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Trax3001BBS writes "A 65-foot (20-meter) crack has been found in Wanapum Dam, one of the major dams along the Columbia River in southern Washington. Water levels are being lowered to both reduce water pressure and give the inspectors access to the area. 'Earlier this week, an engineer noticed a slight irregular "bowing" above the spillway gates near where cars can drive across the dam. When divers finally took a look under water they found a 2-inch-wide crack that stretched for 65 feet along the base of one of the dam's spillway piers.' The article goes on to say, 'Even if the dam doesn't fail, the significance of the damage is likely to require extensive repairs and that, too, could impact the entire Columbia River system. "All these dams coordinate to generate energy on a regional scope," Stedwick said. "If Wanapum is impacted, that has impacts on dams upstream as well as below." Upstream dams would be required to handle more water; there's only one lower dam (Priest Rapids). After that is the last free flowing section of the Columbia river. I've taken walks along that section, and I've seen it deviate (higher or lower) by amazing amount of water, so it can handle the changing flow rate. Making this situation more complex, a large group of people would like that particular dam removed, as well as the one above and below it (think of the fish!). On top of that, after the Priest Rapids dam (downstream from Wanapum Dam) is the Hanford Nuclear Reservation, once a site for Plutonium production. Either of these issues could generate a ton of attention. Personally, I'd like to give the engineer that noticed a slight irregular 'bowing' my congratulations."

I know this is going to kill my karma, but WTF?? That is the most poorly written article I've ever seen on here and I'd wager that most would find it completely off-topic for the site. Combined with the new commenting system, and I think my days here are over. It's been a fun ride, but adios Slashdot.

Um, you know, geeks aren't just interested in the latest software abomination running on 200 incomprehensible layers of poorly documented features to run some game on a cell phone for about a week, you know?

Unless the damn was built after using 3d rendered models and ran through thousands of simulations then it isn't "tech". It took no math or science to build the Erie Canal, the Hoover Dam or the Panama Canal.
In seriousness this is a better story on the site than a story about outstanding student loan debt. The engineering in projects like this and what it will take to fix it requires the same skills as people who design realistic game environments and physics simulators, etc. Many facets all come into play. Anyone who doesn't see this as "news for nerds" should probably go visit the Hoover Dam or tour an aircraft carrier.

It took no math or science to build the Erie Canal, the Hoover Dam or the Panama Canal.

Unfortunately, I had to read the rest of your post three times to make sure you weren't seriously claiming this. It's amazing the number of self-proclaimed nerds who don't seem to understand that technology actually does predate computers.

And he goes on to claim we need "the same skills as people who design realistic game environments and physics simulators, etc." in a comment where he dismissed the importance of student loan debt in the tech. world.

Modern engineering systems using physics based model that are run on accurate geometric models of the terrain, the underlying rock geology, rainfall and a high resolution model of the proposed construction structure (Finite Element Analysis) . All of that geometry is acquired using laser scanners, radar mapping, geological investigation, geophysics, geomagnetics. Then all that data is used to run the simulation.

Modern game engines use physics based systems that work with geometric models created by artists

and I'd wager that most would find it completely off-topic for the site.

Why? It deals with engineering and technology. If it was a crack in a Shuttle SRB seal we'd be discussing it. It may not be cool and sexy like the latest s/w SNAFU, but infrastructure gobbles up a lot of money and its maintenance (or lack thereof) is a major issue in this country and others.

infrastructure gobbles up a lot of money and its maintenance (or lack thereof) is a major issue in this country

You've nailed it. Infrastructure has become invisible, unlauded, boring. Infrastructure is the original stuff that matters.

Aside from entering some engineering field, there are ways that nerds can make a difference. Take this dam for example, clearly a certain level of routine surveillance had not been performed . If divers discover a 2 inch crack, could there have been a half inch or hairline crack some time ago? And could a more thorough use of remote imaging or even acoustic technology have spotted it

It's because the Republicans want us All to die. They killed my mother with a different dam so this is nothing out of the ordinary for Republicans.

Washington state mostly voted for a democrat in the last presidential election. Has a democrat for governor. Has six members who are democrat to four republican in the US house of representatives and both senators are democrats. Is 55 to 43 in favor of the democrats in the lower state house. And is 26 to 23 in favor of the dems in the state senate. But the republicans are responsible for this dam? If that's the case, the democrats in that state should all be shot for gross incompetence. Or perhaps the r

If there is only one dam below Wanapum, this will be easy. But don't miss an opportunity to throw in a totally irrelevant mention of the Hanford nuclear weapons complex - you know, that place that itself gets irrelevantly dragged into any discussion of commercial nuclear power.

irrelevant? *blinks* hanford being downstream from a damned leaking dam is irrelevant? (Here's a map ) *blinks* hanford being the one that was leaking just months ago? http://www.cbsnews.com/8301-20...> maybe it's just me but i see the relevance

Yes. And we don't have to worry about Trojan anymore. But now that I think about it the containment wessel was shipped to Hansford and buried. It would be a real bitch to see that thing floating back downriver.

Point: there are quite a few Columbia River dams downstream of Wanapum, not just one. There is only one below Wanapum and above the free-flowing stretch of the Columbia, but that is only about 60 miles or so. Then there are a few hundred more miles of river with several more dams.

Point: there are many buried reactor cores at Hanford. Hanford is large though, over 500 square miles, and they are not subject to flooding even if the dam was gone.

Point: there are quite a few Columbia River dams downstream of Wanapum, not just one. There is only one below Wanapum and above the free-flowing stretch of the Columbia, but that is only about 60 miles or so. Then there are a few hundred more miles of river with several more dams.

There's a number of dams upstream as well - in fact, above the 49th.

It's kind of interesting since the US has a treaty with Canada over the Columbia river - for a long time, the US has been paying Canada (BC, more specifically) to

Hanford, for the most part, sits high above the Columbia. A few feet of rise in the Columbia would almost certainly change nothing in relation to stored radioactive sludge tanks. Any ground seepage that was going on yesterday will still go on tomorrow, but as a bonus, the additional flow will provide greater dilution... It's a total red herring in this discussion.

The author is correct, but he expressed it in a very awkward way: below Wanapum Dam is Priest Rapids Dam, and below that is the Hanford Reach, a free-flowing section of the river. If Wanapum fails, the Priest Rapids reservoir needs to absorb the entire flood; releasing it will cause flooding in the Hanford area.

The interesting thing about the Hanford reach of the Columbia River is that it is one of the few free flowing sections of the river above Bonneville Dam. Because of the Hanford Reservation it is also undeveloped and as wild as any section of the river in the US. It is home to one of the healthiest runs of Chinook Salmon in the Columbia River system.

Precisely why lowering the Wanapum pool in a controlled manner before it breaches would dramatically reduce the probability that anything would happen to all those cubic kilometers. There will be increased flow through the other dams for a time until this is accomplished, but no net change in the other pool levels.

I believe the biggest problem with cracked dam walls is that moisture gets into the interior of the wall and softens the material which is keeping it strong. Then the crack opens a little bit more, more water gets in and you have a nice exponential curve happening.

There was a rumour about this happening to the hume reservoir in Australia about 20 years ago.

Water doesn't "soften" concrete. H2O is molecularly bound into its structure and is a necessary part of maintaining the strength of concrete. Water invading earthen dams, on the other hand, is a more serious problem.

The steel is bathed in moisture for decades without weakening. Concrete hardens and is stronger under water. Water cracks concrete via the thaw freeze cycle. Water enters the void, freezes, expands, widens the void. But a 60 foot long crack suggests something shifted under the damn.

Rebar can sit outside in the elements for decades. I've got some in my backyard now. Ironically, one of the best corrosion preventatives is surface rust. It's when you combine the moisture with water movement, like in a river or pond, the water can not only corrode it but carry away the surface rust exposing new material to oxidation. Buried in concrete, that oxidation isn't going anywhere, no matter how much water is there. The PH of concrete settles down after a while. For example, you can build some nift

Not true. There's oxygen present in the water itself. Pure water tends to not rust iron, as there is no conductivity to drive the electrochemical reaction. River water is not "pure", but will have lots of salts and other dissolved solids that will raise the conductivity of the water and allow the reaction to occur.

Not sure what you mean by water "invading" earthen dams... but just for the record, earth dams are always full of water that seeps through the component soils to one degree or another. High flow (in cracks say, or because of overtopping) is a problem at it will cause erosion, which may eventually lead to failure, but water "invading" them is not a problem, it's a given.

That being said, you are correct in mentionning that concrete actually requires water to harden through hydration. The problem with cracks i

However they still have the potential to cause similar problems (rust) as reinforcement bars can. That depends on what kind of steel was used and many other things. They do not seem to be a problem at the moment though. The builders also seemed to get lucky as the agregate they used does not react with alkaline moisture which could make it brittle.

It has nothing to do with the moisture. It has to do with pressure. A dam represents a boundary layer between high pressure (behind the dam) and low pressure (air in front of the dam. An intact dam's structure distributes those stresses evenly throughout its structure, and transfers them into the mountains/hills at the sides of the dam. A crack shifts the stresses which would've been borne by the cracked section to the uncracked sections, and particularly at the corners of the cracks. The high stresses at the corners cause the crack to grow. Eventually the crack grows large enough that the stresses are more than the uncracked section can withstand, and the dam fails.

That's what the engineer noticed. The dam was bulging because the uncracked section was holding back so much more stress than its design load that it physically deformed. 65 feet is a damn big crack (no pun intended). That engineer deserves a ticker tape parade in his honor.

The biggest problem with cracking in a concrete dam wall is the stress it creates on the surrounding material, and the concentration of forces created at the crack edges. I know this is/. but might I suggest you read something on crack propagation?

William Mulholland didn't take action when the St. Francis Dam performed similarly, and after his inspection, killed up to 600 people twelve hours after his inspection.

The situation is just a *bit* more complex than your soundbite would indicate - and any repairs made on the cracks he inspected on the 12th of March would almost certainly have been just re-arranging the deck chairs on the Titanic. It's almost certain that the foundation on the west end of the dam had already been fatally compromised and the

It's almost certain that the foundation on the west end of the dam had already been fatally compromised and the cracks were a symptom of the impending failure rather than the cause.

Could the same not be true in this case as well? Even if the dam is irreparably damaged, this will at least hopefully give enough warning to relieve the pressure or in the worst case scenario, evacuate the immediate down-stream area.

Possibly, but I don't think it likely. The St Francis had numerous cracks and symptoms of problems over an extended period of time. (And if you had read TFA, you'll find they are drawing down the reservoir behind the dam, to relieve the pressure.)

(And if you had read TFA, you'll find they are drawing down the reservoir behind the dam, to relieve the pressure.)

Hate to burst your bubble, but that was in the *summary* and it's actually to allow better access to assess the situation. My guess is the will wait until after the assessment to raise the water level back up.

That last free-flowing stretch of the Columbia River that the OP mentions is also the last stretch of Columbia River that maintains spawning habitat. It also accounts for a very large portion of the salmon that return through the Columbia River estuary every year. If removing this dam would open up more spawning habitat, this would not be a bad thing.

I'm sure glad they caught it. China has a similar series of hydroelectric dams. A failure caused a domino effect and when the Banquai dam failed it killed 200,000 people. I know TFA says the failure of this one dam wouldn't kill that many people, but that assumes the sudden tidal-wave-like flood doesn't effect the downstream dams. A domino failure on the Columbia river would be a catastrophe.

The Wanapum dam holds back 796,000 acre feet of water. The next dam on the river has a capacity that is a fraction of that (237,100 acre feet), but the one after that is bigger than both of those combined, but not much.

All told, if we had a domino action of Wanapum and the 4 downriver dams failing, we'd be talking about 5,780,100 acre feet of water flowing past Portland, which would be a devastating event indeed.

This is the problem with Hydro power. This is why we should go 100% solar and not use electricity at night. We can't safely use Hydro, it's too dangerous, the pressure levels and engineering is too dangerous and a single mistake could kill an entire ecosystem.

I don't mean to say coal and oil are safer - they kill far more when used as intended. But the fact that the fuel needs to be delivered to a combustion chamber means you can usually cut off the energy source, limiting the scope of a single accident. That's not the case with hydro - once the water gets moving, there's pretty much nothing anything man-made can do to stop it. All that energy is gonna be released. Likewise, nuclear rates high in risk because the energy density of the fuel is so high - a million times higher than petroleum. Solar and wind would appear to be low-risk, but that's an illusion generated by their low energy density. When you normalize for how many solar panels or wind turbines need to be installed and maintained to generate 1 GWh of electricity, they end up killing more people than nuclear.

Everything has risk. The question isn't how much risk there is per disaster. It's how much risk there is per unit of energy generated.

Actually you do kinda have a point, even though your post is supposed to be a parody of anti-nuclear arguments on safety grounds. It seems that organizations, particularly commercial ones, are terrible at maintaining safety over long periods of time. Safety costs money and the temptation is to just put it off until the individual responsible moves on and it becomes someone else's problem to break the bad news to the people holding the purse strings.

Sure congratulate him for doing his job. But don't think for a minute that this issue wouldn't be seen on major dams because they are, all the time. Dam's are monitored for these issues. Routine and annual inspections are made. This is done precisely to prevent accidents like we've had in the past. Dams must be monitored because water is relentless at finding ways to breach the containment.

I'd like some more information on how these dams' structures are monitored. Embedded sensor networks? Or do they just hope some vigilant employee will notice "something odd"? That would be news for nerds.

An embedded sensor wouldn't do you any good anyway. A dam failure that happened in my state about 20 years (the last) involved water seeping through unknown cracks in the bed rock under the dam that allowed the water to erode a hole in the face of the dam.

For earthen dams they monitor with visual inspections and survey of the top and sides of the dam. Long before the dam fails there will be erosion visible either directly or through sagging surface elevations. Concrete is far more straightforward, beyond cr

There are 5 dams down stream of wanapum, 1 above the free flowing hanford reach and 4 dams below that. River "operations" involve a complicated coordination of all the dams and reservoirs to provide adequate flow for fish and year-round power generation. It is an interesting engineering problem - hacking a river. There is also a computer angle here in that several data centers are located in Grant County (which owns the generation rights) to take advantage of the cheap reliable power. Presumably those data centers are watching this closely. Power rates for everyone in the county will rise if they have less power to sell or if they have to buy power from outside the county.
The system is dependent upon storage for of moving water down stream the river is very interesting in that water flowing through one dam

You're correct. This is an "issue" because it's standard BR procedure, and all federal entities must be notified for this. SOP...

This is not a major problem right now, as it could be solved pretty easily. However, 24 miles downstream is the Hanford area, which borders 520 sq. miles of variously polluted soil. A sudden breach of Wanapum could cause a breach of Priest Rapids dam (~10 miles away) and flood the Hanford area, which has small areas of high radioactive contamination, the likes of which are par

The data centers in Quincy are quite large. Microsoft has a major facility, which is undergoing expansion. So does Yahoo, Intuit, Dell, and Sabey. These are major components of the tax base for the town of Quincy and elsewhere in Grant County. The data centers are highly resilient to power loss, with on-site diesel generators, 24x7 staffing, and all the other protections you'd expect. But prolonged use of the generators, if it becomes necessary, could exceed the permitted run time and accompanying pollution the facilities are allowed. Most likely, power from the other dams the Grant County PUD operates (or elsewhere on the regional power grid) could be routed to the data centers.

There are some other huge electricity consumers in the county. It's the world headquarters of a company that makes photovoltaic components, and also several food processors (all those potatoes from eastern Washington gotta be processed and cooked!). Industrial users might be able to turn down their power usage if there is a regional shortage, but data centers tend to operate at fairly stable 24x7 consumption levels. Major companies like those listed above have redundant facilities, and can shunt processing to other centers if required.

Site selection for major electricity consumers, including data centers, is a fascinating topic. The State of Washington has had various tax incentives to help businesses to choose to build facilities there. Electricity costs are among the lowest in the nation (under 3 cents/kWh for industrial customers). Plus, it makes extensive use of renewable sources, particularly hydroelectric (i.e., dams) and wind energy. Oregon has a similar story to tell, with their own rivers, dams, tax breaks, etc., and is part of why Amazon elected to put a huge facility there.

... much of the region is suffering from drought conditions. While eastern drainages to the Colombia have a fairly robust snow pack, many to west and south of the river are suffering. This would normally suggest the Army Corps of Engineers would want to hold back more water in the reservoirs, but this news impacts such actions. In the mixed new category, storms are currently lining up to dump on the region. Snow pack data is available, here: http://www.nwrfc.noaa.gov/snow/ [noaa.gov] 10-day weather forecast maps, here

this exceeds the excessive inaccuracy ratings for slashdot.
It helps if you actually read the links you include in your article. this page: http://upload.wikimedia.org/wikipedia/commons/e/ec/Pacific_Northwest_River_System.png [wikimedia.org], linked in the article, shows there are 5 dams below the wanapum. apparently the change in color was too confusing for you?
The Columbia is only free-flowing below the Bonneville dam which is just upriver from Portland/Vancouver.

Actually, "bring it on". Bonneville (one of the five dams below it) generates a considerable amount of power for my area. On the other hand, we'll need that water this summer if we don't get more snowpack in the mountains.

It's more about being able to still have agriculture in the hundreds of thousands of acres that get irrigated from the reservoirs behind the dams. These hydropower projects had three objectives, all wildly successful for the last 50 years:

1. Flood control2. Electricity generation3. Irrigation of the high plains surrounding the Columbia River

WTF.. I goggled flesh light thinking it was something I should know but never heard of before. Surprisingly, it's a masturbation product. So why do you think only males who masturbate with a flashlight looking thing will be sent into the depths of the earth and what makes you think there are millions of them?

I mean hell, I can deal with the dinosaurs.. I just don't know about the flesh light things.

Most of the Columbia River dams were built in the 1950s after Harry Truman strong-armed Congress into passing the Flood Control Act of 1950 [wikipedia.org] due to the second largest city in Oregon being wiped off the map [wikipedia.org] when a levy broke in 1948.